This is more like a general question? I need some models for a school project and I have in mind some objects from a mmorpg. Do you know if it’s possible to use in Unity models taken from installed pc games?
No. once a video game / program goes through a compiler or “build process” its its packed into a binary format that is extemely difficult to read externally . Especially an entire model.
From a technical point-of-view, it’s normally pretty trivial to “rip” assets - including models and textures - from a game. From a legal point-of-view, however, this is almost always expressly prohibited by the EULA.
For a school project, I recommend you visit somewhere like blendswap.com instead, which clearly states the licence under which models can be used.
Your biggest technical issue will be figuring out how that specific game bundles their model and texture data, and how to extract it. Some games that will be easy, some extremely difficult. You’re not going to find instructions on how to do that here.